Meter for measuring brightness of bleached fibers and controlling the bleaching process

ABSTRACT

Apparatus for continuously controlling the bleaching of fibers and for continuously measuring and recording the brightness of light reflected from the bleached fibers having a bleaching tank, means for feeding fibers to the tank, means for feeding bleaching agents to the tank, means for feeding bleached fibers from the tank, a drum for forming the bleached fibers into a mat on the drum, a housing open at one end and closed at its sides and opposite ends supported on the mat on the drum on rollers, a light source and a light-responsive phototube in the housing, means in the housing for directing light from the light source onto a mat at the open end of said housing and for directing reflected light from such mat to the phototube and means responsive to the phototube and light reflected to the phototube for controlling the feed of bleaching agent to the bleaching tank and for recording the brightness of the mat.

D United States Patent Inventor James II. Chappelle Keusington, Georgetown, S.C.

Appl. No. 31,857

Filed May 1, 1970 Patented Sept. 21, 1971 Assignee International Paper Company New York, N.Y.

Continuation of application Ser. No. 535,402, Mar. 18, 1966, now abandoned.

METER FOR MEASURING BRIGIITNESS OF 'BLEACIIED FIBERS AND CONTROLLING THE Primary Examiner-S. Leon Bashore Assistant ExaminerR. H. Tushin AllorneyCharles B. Smith ABSTRACT: Apparatus for continuously controlling the bleaching of fibers and for continuously measuring and recording the brightness of light reflected from the bleached fibers having a bleaching tank, means for feeding fibers to the tank, means for feeding bleaching agents to the tank, means for feeding bleached fibers from the tank, a drum for forming the bleached fibers into a mat on the drum, a housing open at one end and closed at its sides and opposite ends supported on the mat on the drum on rollers, a light source and a lightresponsive phototube in the housing, means in the housing for directing light from the light source onto a mat at the open end of said housing and for directing reflected light from such mat to the phototube and means responsive to the phototube and light reflected to the phototube for controlling the feed of bleaching agent to the bleaching tank and for recording the brightness of the mat.

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PATENTED SEPZI ran SHEET 1 OF 3 PATENTED SEI'ZI I97! SHEET 2 OF 3 PATENTED SEPZI um SHEET 3 UF 3 METER FOR MEASURING BRIGIITNESS OF BLEACI'IED FIBERS AND CONTROLLING THE BLEACHING PROCESS This application is a continuation application of US. Ser. No. 535,402, filed Mar. 18, 1966, now abandoned. This invention relates to color measurement and control and, more particularly, to color measurement and control of pulp stock in papermaking.

In the manufacture of paper, particularly kraft, it is the usual practice to bleach the fibers before forming the fibers in the sheet. This is accomplished by chemically treating, and washing, the fibers. For obvious reasons, it is desirable, after treatment, that the fibers be substantially of standard and uniform color. To attain such a standard and uniform color, it is the usual practice to vary the chemical treatment, as needed, to suit the needs of the fibers.

To an appreciable extent, fiber bleaching, heretofore, has been controlled by an operator who, by visual observation of the bleached fibers and manual adjustment, increased or decreased the chemicals added to the system. Periodically, a handful of the bleached and washed fibers is withdrawn from the system, repulped with clean water, hand sheeted and dried. The color of the repulped hand sheeted and dried sample is then measured and compared with a known standard. Such sampling, repulping, hand sheeting, drying and measuring takes a substantial amount of time and tests only a very small sample which may not be representative of the fibers in the system. In addition, if the fibers are not properly sheeted, or the sheet is overdried or underdried, an erroneous measurement may result.

One of the objects of the instant invention is to provide improved apparatus for measuring and controlling color.

A further object is to provide such apparatus for measuring and controlling the color of pulp stock in paper-making.

A still further object is to provide such apparatus which will be continuous.

Still a further object is to provide such apparatus which will continuously measure and automatically control the color of the pulp stock.

These and other objects will be more apparent from the following description and the attached drawings in which FIG. 1 is a flow diagram of a paper-fiber-bleaching plant incorporating the apparatus of the instant invention;

FIG. 2 is a side elevational view, partly in sectionof the measuring apparatus of the instant invention;

FIG. 3 is a view, partly in section, taken along the line 3-3 of FIG. 2 and showing, in diagram, the electrical controls of the measuring apparatus; and

FIG. 4 is a further diagram of the electrical controls of FIG. 3.

In the instant invention, the fibers are blended with water to form a slurry and are chemically treated, bleached, washed and matted in the conventional manner. After bleaching, the whiteness or brightness of the bleached and washed mat is continuously measured and recorded. The amount of bleaching chemicals is automatically increased or decreased, as the case may be, depending on the whiteness or brightness of the mat. 7

Referring now to FIG. 1, the fibers to be treated are mixed or blended with water in a blending chest, not shown, and are pumped, through mixer 2, into the bottom of tank 4. Chlorine is added to, and mixed with, the fiber slurry in mixer 2.

Tank 4, as are the other treatment tanks discussed later, is open at its top. Thus, the slurry overflows from the top of tank 4 and isdischarged into box, or chest, 12 of vacuum forming drum 14. The fibers are matted on drum 14 from chest 12, the matted fibers are water sprayed and washed as drum 14 rotates and the washed, matted fibers are discharged from drum 14 into box, or chest, 16. The fibers are withdrawn from chest 16 through line 18.

Sodium hydroxide is fed into line 18 through line 20 and, with the fibers, is fed into the bottom of tank 22. The fibers overflow from the top of tank 22 and are discharged into box, or chest, 24 of vacuum forming drum 26. The fibers are again vacuum formed into a mat on drum 26, are water sprayed and washed and are discharged into box, or chest, 28. Sodium hypochlorite and sodium chloride are added to the fibers in chest 28 through bleach feed line 29 and the fibers are withdrawn from chest 28 and fed through feed means or line 34 into the bottom of tank 36. The rate of flow, or amount, of sodium hypochlorite is controlled by motorized valve 31, as will be described later.

The fiber slurry moves upward through bleach tank 36, overflows the top of the tank into box, or chest, 38 of vacuum drum 40. The fibers are again vacuum formed into a mat on drum 40, are water sprayed and washed and are discharged from drum 40 into box, or chest, 42. As the fiber mat is rotated on drum 40 from chest 38 to chest 42, and after the mat is water sprayed and washed, the mat passes under the photoelectric measuring apparatus, generally designated 44. The photoelectric measuring apparatus and its operation will be described in greater detail later.

From chest 42, the fibers are discharged through line 46 into the bottom of tank 48. The fiber slurry moves upward through tank 48 and overflows the top of the tank into box, or chest, 52 of vacuum drum 54. For reason described later, chlorine dioxide may be added to the fiber slurry, as it enters the bottom of tank 48, through motorized valve 49 and line 50.

The fibers are reformed into a mat on vacuum drum 54, the mat is water sprayed and the fibers washed and the fibers are discharged into box, or chest, 56. After the mat is water sprayed and washed and before the matted fibers are discharged from the drum, the mat passes under photoelectric measuring apparatus, generally designated 58.

With the exception of photoelectric measuring apparatus 44, 58, that are identical, and motorized valves 31, 49, also identical, the foregoing arrangement is illustrative of a line bleaching plant and the process of the plant in which the apparatus of the instant invention, which will now be described, is useful and may be incorporated. It is to be understood that the instant apparatus is useful and may be incorporated in other arrangements.

Referring to FIGS. 2 and 3, the photoelectric measuring apparatus will be described as mounted and supported on vacuum drum 40. In some systems a single photoelectric measuring apparatus may be sufficient. In other systems, especially where it is desirable to bontrol the final color of the bleached fibers to a more accurate and more precise degree, additional photoelectric measuring apparatus, may be added to the system. Thus, in the flow diagram of FIG. 1 a second photoelectric measuring apparatus mounted and supported as on vacuum drum 40, is positioned on vacuum drum 54.

In FIGS. 2 and 3, photoelectric measuring apparatus 44 includes a housing 70 of metal, such as aluminum, or other suitable material, supported by rollers 75, 77, rotatably mounted on frame 79, 79', fixed to housing 70. Apparatus 44 is held in position by air cylinders 83, 83', pivotally connected at one of their ends at 81, 81' to housing 70, and at their opposite ends to stationary beam 85.

Housing 70 is opened at its bottom and, at either side of the top, has upwardly and outwardly extending legs 72, 74 and, at its center, upwardly extending leg 76. For reasons that are obvious, legs 72, 74, 76 each have covers 78, 80, 82, respectively. Floodlamp 84, preferably a ISO-watt lamp, is mounted in socket 86 in leg 72. Air is supplied to leg 72 through tube 88 from a source, not shown.

Floodlamp 90, preferably also a ISO-watt lamp, is mounted in socket 92, in leg 74. Air is supplied to leg 74 through tube 96 from a source, not shown.

The upper end of leg 76 of housing 70 is closed by wall 100 which, with the exception of aperture 102 in wall 100, forms a lighttight seal adjacent the upper end of the leg 76. Blue filter 104, for example, a 457 millimicron filter, is positioned over aperture 102. Cap 82 is lighttight, and light-responsive phototube 106, responsive to light passed by filter 104, is positioned in leg 76 intermediate wall I00 and cap 82, in align- The whole was passed into an oven at 150 C., and kept there for 1-2 minutes. Thereafter, onto the previous layer a second layer (foamed) was spread. which consisted of:

PVC, paste making resin having a K-value of 72 dioctyl phthalate 100 parts (by weight) 80 parts (by weight) The initial thickness of this layer was 200 microns.

The whole was then passed into an oven at 200 C. and kept there for l-2 minutes. The release paper was then removed. The system was then subjected to a slight tension in order to facilitate the separation of those components that were incompatible with each other; then the system was coupled to a cotton jersey fabric (with the second layer adjacent to the fabric), after preliminarily having spread on the fabric some plastisol of the first layer which served as a binder. Said coupling occurred in about 1 minute in an oven heated to ISO-170 C.

The poromeric material thus obtained showed the following air transpiration rates:

Pressure (mm. Hg)

The release paper was then removed and the system was subjected to a slight tension and subsequently was coupled to a jersey fabric made of polyamide fibers, the second layer being adjacent to the fabric after preliminary having spread on the fabric some plastisol of the first layer which serves as a binder.

The poromeric material thus obtained shows the following air transpiration rates:

Pressure cm. of air (mm.Hg) hr. cm.

4U 80 60 121 I00 205 ISO 270 Example 3 100 parts (by weight) PVC, paste making resin with a phototube in said housing, means in said housing for directing reflected light from said mat at the open end of said housing to said first phototube, a second light-responsive phototube, means for shielding said second light-responsive phototube, means for shielding said second light-responsive phototube from extraneous light, said shielding means being affixed to the sides of the said housing, an aperture in said shielding means, a means for reflecting a portion of the light from said light source in said housing, said means for reflecting a portion of said light being-situated intermediate the light source and the fiber slurry and in closed juxtaposition to said aperture in said shielding means, means for comparing the light detected by the first light-responsive phototube with the light detected by the second light-responsive phototube, means responsive to said comparative signal for recording the brightness of said mat, and means responsive to said comparative signal for controlling said means for feeding bleaching agent to tank.

2. An apparatus as recited in claim 1 including a second light source in said housing for further illuminating said bleached fibers.

3. An apparatus as recited in claim 2 including filters intermediate said light sources and said phototubes.

4. An apparatus for continuously controlling the bleaching of fibers and for continuously measuring and recording the brightness of light reflected from said bleached fibers comprising, a bleaching tank, means for feeding fibers to said bleaching tank, means for feeding bleaching agent to said tank, means for discharging bleached fibers from said tank, a drum, a means for forming said bleached fibers onto a mat on said drum, a housing open at one end and closed at its sides and opposite end, roller means for supporting said housing on said mat with said open end of said housing facing said mat, a

' first light source in said housing, a second light'source in said housing, a first light-responsive phototube in said housing, a shielding box affixed to one side of said housing such that the side of said housing forms on wall of the shielding box, s second light-responsive phototube in said shielding box, an aperture in said wall of said housing which forms part of the shielding box, a reflecting means affixed to the internal portion of the housing in close juxtaposition to the shielding box aperture in said housing, said reflective means being situated intermediate second light source in said housing and the open end of the housing to direct a portion of the unreflected light from the second light source to the second light-responsive phototube to serve as a reflecting standard, means in said housing for directing reflected light from said mat at the open of said housing to first phototube, means for comparing the electrical signal from the first light-responsive phototube to the signals from said second light-responsive phototube to yield a comparative measurement of the reflectivity of the bleached fibers, means responsive to said comparative measurement for recording the brightness of said mat, and means responsive to said comparative measurement for controlling said means for feeding bleaching agent to said tank.

An apparatus as recited in claim 4 including a first light filter intermediate the open end of said housing and first phototube and a second light filter intermediate said means for reflecting a portion of the light from said second light source and said second light source.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.607.623 Dated September 21, 1971 Inventor(s) James H. Chappelle It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 2 "GO-cycle 115 v. AC" should be 6O cycle 115 V. AC. --5

Column 3, line 26, "as on leg" should be as one leg Column 3, line 29, "20 v. DC" should be 20 V. DC- --5 Column 3, line ML, "of the required level.

should be at the required level.

Column 3, line 7 for special variations" should be for spectral variations Column line 5, "at a constant valve, should be at a constant value, -3

Column 5, line t is repeated at line 5;

Column 6, line 5, on wall" should be one wall -5 Column 6, line 5, "s" should be a --5 Column 6, line 15, after "open" insert end DRM F o-105 10-69 O USCOMM-DC sosmw es U 5 GDVERNMENI PRiNTING OFFICE '19690-35633 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 'g o 5g'g Dated September 21, 1971 Inventor) James H. Chappelle PAGE 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 16, to first phototube, should be to said first phototube,

Column 6, line 17, "the should be said Column 6, line 2 L, delete "5;

Column 6, line 25, before "An" insert 5,--;

Column 6, line 26, and first phototube should be and said first phototube Signed and sealed this 4th day of April 1972.

(SEAL) Attest:

EDWARD M,FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents ORM PO-IOSO (10-69! USCOMM-OC scan-Pen 

2. An apparatus as recited in claim 1 including a second light source in said housing for further illuminating said bleached fibers.
 3. An apparatus as recited in claim 2 including filters intermediate said light sources and said phototubes.
 4. An apparatus for continuously controlling the bleaching of fibers and for continuously measuring and recording the brightness of light reflected from said bleached fibers comprising, a bleaching tank, means for feeding fibers to said bleaching tank, means for feeding bleaching agent to said tank, means for discharging bleached fibers from said tank, a drum, a means for forming said bleached fibers onto a mat on said drum, a housing open at one end and closed at its sides and opposite end, roller means for supporting said housing on said mat with said open end of said housing facing said mat, a first light source in said housing, a second light source in said housing, a first light-responsive phototube in said housing, a shielding box affixed to one side of said housing such that the side of said housing forms one wall of the shielding box, a second light-responsive phototube in said shielding box, an aperture in said wall of said housing which forms part of the shielding box, a reflecting means affixed to the internal portion of the housing in close juxtaposition to the shielding box aperture in said housing, said reflective means being situated intermediate second light source in said housing and the open end of the housing to direct a portion of the unreflected light from the second light source to the second light-responsive phototube to serve as a reflecting standard, means in said housing for directing reflected light from said mat at the open end of said housing to said first phototube, means for comparing the electrical signal from said first light-responsive phototube to the signals from said second light-responsive phototube to yield a comparative measurement of the reflectivity of the bleached fibers, means responsive to said comparative measurement for recording the brightness of said mat, and means responsive to said comparative measurement for controlling said means for feeding bleaching agent to said tank.
 5. An apparatus as recited in claim 4 including a first light filter intermediate the open end of said housing and first phototube and a second light filter intermediate said means for reflecting a portion of the light from said second light source and said second light source. 